Coo: Tooi Umi kara Kita Coo

On the picturesque island of Pagopago in the Fiji archipelago, young Obata Yousuke enjoys a tranquil life with his father, Tetsuo, an expert in oceanographic biology. Their peaceful existence is disrupted when a fierce storm sweeps through, leading Yousuke to the lagoon on his Jet Ski, where he makes an extraordinary discovery—a mysterious baby dinosaur. He brings the creature, whom he affectionately names Coo, to his father's lab, where they begin to uncover its fascinating origins.

As Coo matures, it becomes apparent that this remarkable marine reptile, a baby plesiosaur from the age of dinosaurs, holds secrets that attract the attention of the French secret service. Tasked with safeguarding France's nuclear interests in the region, they pose a new threat to the tranquility of Pagopago, drawing Yousuke and Tetsuo into a web of adventure and intrigue that challenges their understanding of both the past and their future.